The influence of predation risk on mate signaling and mate choice in the lesser waxmoth Achroia grisella

Mating signals are often conspicuous and can be eavesdropped on by predators. Therefore, it is expected that predation risk will shape the evolution of sexual communication in both senders and receivers. Males of the lesser waxmoth Achroia grisella produce ultrasonic signals to attract females, and females have preferences for certain signal traits. When they detect predator cues such as bat echolocation calls, males typically stop signaling and females freeze. Here we examine different ways in which predation risk affects male signaling and female choice. We exposed calling males to predator cues under three different treatments: in isolation, within a simulated lek composed of attractive males, or within a simulated lek of unattractive males. We also tested if female choice depends on predation risk by submitting females to a two-choice test between an attractive and an unattractive signal, in the presence and the absence of predator cues. We found that risk-taking behavior is not only impacted by the presence of competitors, but by the competitors’ attractiveness as well. Additionally, more attractive males take more risks when calling in isolation, but not when lekking. In females, we found that preference for the more attractive call disappeared when the attractive call was associated with higher predation risk. These results reinforce the trade-off between traits that increase survival and mate attraction, and bring new insight into the evolution of leks in this species.